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This is why you don't poke wires with a test light

Discussion in 'Western Plows Discussion' started by mishnick, Dec 14, 2014.

  1. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    Recently an irate plow owner came in complaining that his plow lights were spontaneously switching between the plow and the truck. He checked all the basics, wiggled the plugs, cleaned his battery terminals and checked the fuses. Finally he gave up and brought it to our shop. I expected it would be corroded pins at the light plug, broken wires near the plug or maybe even a damaged isolation module. So I just swapped in a few easily substituted items but no change.... Finally I brought it into the shop and took a serious look at it. Usually this kind of thing is pretty quick to troubleshoot but this one made me work for it. The intermittent behavior was confusing. I would test for voltage at all the key points and everything seemed fine... Suspecting a voltage drop I knew I had to test the key points under load so I used breakout plugs rather than just opening the plugs to test for voltage. Eventually I found that there was only 8 volts (under load) / 12 volts (no load) on the red wire, that comes directly from the battery positive post, at the four pin plug that connects the control cable to the headlight harness. That same wire goes through another 4 pin plug on the end of the control harness where it connects to the plow battery cable. That plug was fine but the next one down the line was not getting full voltage. So.... I was just about to pull back the loom when I saw what looked like a little red snake that swallowed a rat! See photo 1.

    If you look close you can see where someone used one of those sharp, penetrating test light probes to test the wire. The plow is only one year old so you can see how much damage such a seemingly innocent act can cause.

    Using a weatherpack pin removal tool I pulled the wire out of the plug and cut it just a few inches back from the damage. See photo 2

    Finally I put a few inches of new wire and a new weatherpack male connector on the end and pushed it back into the 4 pin plug. See photo 3

    Once this bit of corroded wire was replaced the plow was again reliable and on it's way....



  2. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,750

    Well, since you started this....I'll add.
    This is what happens to scotch locks outside


  3. rjigto4oje

    rjigto4oje PlowSite.com Addict
    Messages: 1,258

    I wonder how the guy's finger looks. They should have used a paper clip to back probe the terminals I can't tell you how many times I have seen this before especially in the rear usally after they put a new fuel pump in and it still wont start
  4. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    Those scotch lock tap-in connectors are useless! Some plow manufacturers still include them in their installation kits. I am proud to say that Western does not! They send the un-coated butt connectors and a piece of double heat shrink tube. Seems that all the trailers we import from the US have this kind of connector Big Tex and Load Trail both use them. It's kind of a common joke here in Canada that these trailers were intended for Florida.

    Both back probing with a poker and these scotch lock connectors are the result of the same economic problem. Everyone wants things done cheap and for the mechanic, these things make the customer happy immediately and keep them happy just long enough that they don't hold you responsible for it when they cause a failure.
  5. to_buy

    to_buy Senior Member
    Messages: 217

    God i hate that, I am a crimp, solder and heat shrink guy. I also swear by di-electric grease
  6. peteo1

    peteo1 PlowSite.com Addict
    Messages: 1,658

    I hate those things. I'd rather take the time to crimp and heat shrink so I know it won't fail in the next couple weeks
  7. Dogplow Dodge

    Dogplow Dodge 2000 Club Member
    from NJ
    Messages: 2,544

    When we live in NJ, it's the only way to fly....
  8. timboy

    timboy Member
    from Ny
    Messages: 66

    I grind my teeth everytime that I see a scotch lock,there is a Fisher plow dealer in the greater Albany area of NY that uses them and I hate fixing their crap installs!
  9. FourDiamond

    FourDiamond Senior Member
    Messages: 129

    We call those connectors Tap-a-crap.